Heating element for cigar lighters



NOV. 8, 1960 L, E, FENN Q 2,959,663

HEATING ELEMENT FOR CIGAR LIGHTERS Filfid NOV. 12, 1952 I/II 26 4 26INVENTOR BY M51 W ATTORNEYS United States 2,959,663 HEATING ELEMENT FGRCIGAR LIGHTERS Filed Nov. 12, W52, Ser. No. 320,071

Claims. (Cl. 219-32) This invention relates to electric cigar lighterssuch as are used in automobiles, boats, aircraft and the like.

Where such lighters are produced for operation on twelve-volts potentialthe structure of the usual six-volt lighter is utilized, changing onlythe specifications and construction of the heating coil or wire to adaptit to twelve-volt use. The twelve-volt coil is made of thinner wire andhas a greater strength, resulting in a greater number of turns. Due tothe lack of mechanical strength inherent in this organization the coilis impregnated with a ceramic composition which, when it hardens, keepsthe convolutions of the coil in place and prevents the coil from failingelectrically due to physical displacement of its turns.

While such a twelve-volt coil has in general proved to be satisfactoryin use, it is more expensive to produce than the six-volt coilconsisting of a shorter length of heavier wire, since the latter hassufiicient strength to be self-supporting in the heating element cup.Also, the twelve-volt, ceramic-supported coil does not retain acherry-red heat as long as is desired, requiring re-energization ifseveral lights are to be obtained.

The above disadvantages of lack of sturdiness and heat retention intwelve and higher-voltage coils have been overcome by the presentinvention, and an object of the invention is to provide an improvedtwelve and highervoltage heating element coil of small, compactconstruction suitable for incorporation in standard-diameter heatingelement cups, which coil is mechanically sturdy enough for ordinaryusage without the need of ceramic support even though it has more turnsof a thinner wire.

Another object of the invention is to provide an improved heatingelement coil as above set forth, in which the retention of heat ismaterially increased, so that the coil maintains a cherry-red ignitiontemperature for a longer period, eliminating the necessity forre-energization if several lights are required.

I accomplish this by the provision of a novel coil structure which ischaracterized by the turns thereof engaging and being nested with eachother, the Wire or ribbon of the coil being formed transversely of itslength so as to be substantially concave or hollow on one face andsubstantially convex or bulging on the other. Thus when the ribbon iswound into a spiral the convolutions will readily nest with each otherand be mutually supporting. The complete spiral may be encased in thestandarddiameter, shallow cup and the ends welded in the usual manner,and I have found that by so nesting the turns and allowing them toengage each other they will remain in a flat plane within the cup andwill not be dislodged therefrom during use of the lighter.

The formation of the wire need not be perfectly curvilinear transverselyof its length in order to effect the said nesting of the turns. Forexample, the wire may be given a channel-like cross section or a flat-Vcross section or other shapes by which a nesting or mutually supportingstructure is had. The touching of the turns is not elecatent icetrically of serious consequence, since short-circuiting of the coil canbe effectively prevented by an insulating oxide coating on the wire.

Another object of the invention is to provide an improved, small andcompact, high voltage heating coil having adjacent turns contacting eachother as set forth above, wherein effective electrical insulation of theturns is had throughout the life of the coil.

In accomplishing this I provide a thin aluminum coating on the wire andoxidize the coating by suitable heating of the coil. The oxidizedaluminum provides an efficient and effective insulation which preventsshortcircuiting of the adjacent contacting turns. I prefer to form theheating element by coiling the aluminum coated wire, prior to theoxidation of the aluminum, into a spiral shape, the wire being benttransversely of its length to enable a nesting of adjacent turns to behad. I then incorporate the spiral coil in the heating element cup andweld the ends of the wire to the cup and central stud thereof. Afterthis has been done, I pass a heating current through the coil to causethe aluminum coating thereof to melt and oxidize, thereby to effectivelyinsulate the coil convolutions from each other. Oxidation of the coilmay be effected in other ways, as for example, by high frequencyheating, as will be more fully brought out in following paragraphs.

Such a heating coil, made in accordance with this invention, iseconomical to fabricate, rugged and durable, effective for use in twelveand twenty-four volt lighters, and because of its concentrated metallicmass, retains a cherry-red temperature for a relatively long time.

Other features and advantages will hereinafter appear.

In the accompanying drawings:

Figure 1 is a side elevational view of a cigar lighter made inaccordance with the invention, a portion of the holding device beingbroken away to reveal the igniting unit.

Fig. 2 is an enlarged fragmentary axial sectional view of a cigarlighter igniting unit having a heating element made in accordance withthe invention.

Figs. 3, 4, 5 and 6 are transverse sectional views of heating elementwires made in accordance with the invention.

Figs. 7 and 8 are fragmentary axial sectional views of spiral heatingcoils, illustrating further modifications of the invention.

Fig. 9 is a fragmentary axial sectional view of a spiral heating coilillustrating another modification of the invention.

Referring to Figs. 1 and 2 the cigar lighter shown therein comprises aholding device 10 having a tubular body 11 secured to an instrumentpanel 12 by a screw sleeve 13. The holding device it) has bimetallicfingers l4 constituting a clip for engagement with a shallow cup 15 of aremovable igniting unit 16. The unit 16 comprises a plug-like body 17having a knob 18 at its front end, the rear end of the body 17 carryingthe cup 16. As seen in Fig. 2, within the cup 15 there is provided aspiral heating coil 19 having its outer end 20 welded to the cup and itsinner end 21 welded to the head 22 of a rivet 23 which secures the cup15 to the body 17.

In accordance with the present invention the heating element 19 is woundof a flat wire or a ribbon which is formed transversely of its length insuch a manner that the convolutions of the coil will nest with eachother and prevent misalignment of any turn or turns. The wire may beformed to have various shapes; in Fig. 2 the flat wire is curvedtransversely of its length to provide on one side a concave face 24,Fig. 3, and on the other side a convex face 25. The Wire may be formedas in Fig. 4 wherein the edge portions 26 are bent to lie in a flatplane, the

intermediate portions being curved to provide concave and convexsurfaces. In Fig. 5 the wire is shown as being roughly of channel shape,having a flat central portion 27 and angularly extended edge portions 28formed to effect flanges of the channel. In Fig. 6 the heating coil wireis shown as having a flat V-shape in cross section, with angularlydisposed planar portions 29 joined together by a bend 30 extendinglongitudinally along the center of the wire.

In Fig. 7 the heating coil wire is concave-convex, but the side edgeportions 31 have less thickness than the center portion 32. In Fig. 8the wire is concavo-convex with the edge portions 33 thicker than thecenter portion 34.

In Fig. 9 a fragmentary section of a heating element 1% is shown,wherein the wire ribbon is formed transversely to provide a deeperhollow or groove than that shown in Figs. 2, 3, 7 and 8. By thisconstruction a more effective mutual support of the coil convolutions ishad.

In each of the above instances it will be seen that the formed wire maybe wound into a spiral coil wherein the convolutions nest with eachother, as shown in Figs. 2, 7 and 8, thereby locking each individualturn to its adjacent inner and outer end. I have found that the entirecoil assembly when so made is sturdy and able to withstand the effectsof continued usage without causing de formation of the turns and failureof the heating element. While I have shown a number of shapes of wirewhich will provide for a nesting or interlocking effect when Wound intoa spiral, it should be understood other shapes than those shown may alsobe utilized to obtain this result, and thereby come within the scope ofthe invention.

By virtue of the compactness of the coil, and because of itsconcentrated metallic mass it will retain a cherryred heat longer thanthe previous coils in which the turns are spaced apart and provided withceramic composition in the spaces to insulate and support the coilconvolutions.

The shaping of the wire or ribbon may be readily accomplished by a highspeed rolling operation whereby there would be no reduction in the rateof production of the wire. When the formed wire is made into a heatingcoil with the turns nested the presence of oxidation on the surface ofthe wire will prevent damage to the coil from short circuit whenadjacent turns touch each other as shown in Figs. 7 and 8.

By the present invention I provide an effective oxide coating on thewire, which efi'iciently insulates the adjacent turns even though thesetouch each other. This coating is formed by depositing or otherwiseapplying aluminum in a thin layer to the outside of the wire and thenheating the wire to cause the aluminum to become oxidized whereby itwill act as an effective low-voltage insulator which will notdeteriorate or be easily dislodged during the use of the coil.

In carrying out my invention, by which efiective insulation of the turnsof the coil is provided, several procedures or methods may be employed.The wire after being coated with the aluminum may be wound into a spiralshape, placed in the heating element cup, and the ends of the wirewelded to the cup and the central stud thereof. With the turns nested ineach other and in substantial engagament, the coil is energized bypassing a heating current through it. This will cause the aluminum tomelt and to be oxidized, effectively providing a desirable, low-voltageinsulation between the adjacent turns. During the heating of the coilthe melted aluminum will be retained and prevented from dropping outfrom between the coil convolutions by the transverse shaping of the wireand nesting of the convolutions, and by the engagement between adjacentconvolutions. The melted aluminum will not flow appreciably, but insteadwill be quickly oxidized to provide an effective insulation.

My improved process may be advantageously utilized with all types ofmetals used for heating coils. Certain heating element alloys, forexample, have aluminum in their composition, and when these alloys areheated sufficiently the exposed surface of the wire will be coated withaluminum oxide which provides a certain degree of insulation. One suchalloy, known commercially as Kanthal D, consists of 3 /2 aluminum, 23%chromium, 2% cobalt and 7l /2% iron. If wire formed of this alloy iscoated with aluminum and processed as above, the resultant oxide willprovide an insulation superior to that obtained without the coating.Other alloys, such as nickel chrome, which are devoid of aluminum intheir make-up, do not provide self-insulation when heated. Instead, theoxide formed on nickel chrome alloys is conducting and results inshort-circuiting of the coil convolutions of the coil. However,regardless of the alloy used, the provision of a preliminary aluminumcoating on the wire will result in a very effective insulation of theturns of the coil when the wire is properly heated and its surfaceoxidized.

Another procedure by which the aluminum coating on the wire may beadvantageously oxidized is to coil the coated wire into a spiral, clampthe ends in suitable metal clamps and then subject the coil tohigh-frequency heating. The portion of the coil not clamped will becomeincandescent and the aluminum coating thereof will become thoroughlyoxidized to provide an effective insulation. The clamped ends of thecoil will not be heated enough to melt or oxidize the aluminum duringthis opera tion, by virtue of the clamps conducting the heat awayrapidly. Upon completion of the induction heating, the clamps may beremoved and the ends of the coil, which are not oxidized, may be weldedto the heating element cup and central stud thereof.

Variations and modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

I claim:

1. An igniting element for a cigar lighter comprising a spiral ignitingcoil having its convolutions closely spaced and engageable with eachother, said coil being wound of metal ribbon having an integralinsulating surface, said ribbon being curved transversely of its lengthto provide a concave face on one side of the ribbon and a convex face onthe other side of the ribbon and the convolutions of the coil beingnested with each other to effect a mutual support of said convolutions.

2. An igniting element for a cigar lighter comprising a spiral ignitingcoil having its convolutions closely spaced and engageable with eachother, said coil being wound of metal ribbon having an integralinsulating surface, said ribbon being bent transversely to form ashallow longitudinally-extending groove,,thereby to provide a concaveface on one side of the ribbon and a convex face on the other side ofthe ribbon and the convolutions of the coil being nested with each otherto effect a mutual support of said convolutions.

3. An igniting element for a cigar lighter comprising a spiral ignitingcoil having its convolutions closely spaced and engageable with eachother, said coil being wound of metal ribbon having an integralinsulating surface, said ribbon being bent transversely to formlongitudinally extending flanges on the side edges of theribbon and theconvolutions of the coil being nested with each other to effect a mutualsupport of said convolutions.

4. An igniting element for a cigar lighter comprising a flat shallowcircular metal cup; a stud insulatedly secured to the center of the cupand extending into the cavity thereof; and a spiral igniting coildisposed in said cup about the stud and having its ends secured to thecup and stud, said coil being formed of metal ribbon having an integralinsulating surface, said ribbon being shaped transversely of its lengthto provide a hollow face on one side and a substantially rounded face onthe other side and the convolutions of the coil being nested with eachother to eifect a mutual support of said convolutions.

5. An igniting element for a cigar lighter comprising a spiral ignitingcoil having its convolutions closely spaced and engageable with eachother, said coil being wound of metal ribbon having an integralinsulating surface, said ribbon being bent transversely of its length toprovide a hollow face on one side of the ribbon and a bulging face onthe other side of the ribbon and the convolutions of the coil beingnested with each other to effect a mutual support of said convolutions,said coil being characterized by a compact, relatively dense metal licmass having a high degree of heat retention.

6. The invention as defined in claim 5 in which the convolutions of thecoil are in engagement with each other, and in which the coil has acoating of aluminum oxide to provide for electrical insulation betweenthe turns.

7. A cordless electric cigar lighter plug of the type adapted to behoused and heated in a socket and to be separated therefrom for use, aheating element comprising a spirally wound annulus of resistance ribbonof segmental tubular cross-section along at least a portion of itslength, successive courses of said spiral being substantially in contacteach with the next whereby said annulus resists deformation in an axialdirection, said courses being insulated from each other at their pointsof contact solely by an insulating oxide formed on the surface of saidribbon, terminals for said heating element, one of said terminalscomprising a metallic carrier on said plug connected to the outer end ofsaid heating element.

8. The invention as defined in claim 7, wherein said carrier is a cupenclosing said heating element.

9. The invention as defined in claim 7, wherein said ribbon issubstantially V-shaped in cross-section.

10. The invention as described in claim 7, wherein said ribbon issubstantially arcuate in cross-section.

References Cited in the file of this patent UNITED STATES PATENTS515,280 Brown Feb. 20, 1894 1,275,785 Stratton Aug. 13, 1918 1,637,033Basch July 26, 1927 1,746,244 Diack Feb. 11, 1930 1,946,434 Bach Feb. 6,1934 2,062,701 Cohen Dec. 1, 1936 2,085,431 Johnston June 29, 19372,088,949 Fekete Aug. 3, 1937 2,157,050 Bilger et al. May 2, 19392,269,394 Cuno et al. Jan. 6, 1942 2,287,460 Wagenhals June 23, 19422,596,325 Cerny May 13, 1952 2,628,921 Weinrich Feb. 17, 1953 OTHERREFERENCES Woldman & Metzler, Engineering Alloys, 2nd edition, 1945,published by American Society for Metals; page 200.

Woldman; Engineering Alloys, 3rd edition, 1954; published by AmericanSociety for Metals, pages 238, 810.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION *5 Patent No. -2:959,663 November 8, 1960 Lawrence E. Fenn It is hereby certified thaterror appears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column '1 line 22 for etrengtln"v read length Signed and sealed this25th day of April 1961'a (SEAL) Atteet:

ERNEST w. SWIDER Attesting Ofiicer DAVID L LADD I Commis sioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION A;

Patent No 2,959,663 November 8, 1960 Law rence E. Fenn It is herebycertified that error appears in the printed specification of the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

Column '1, line 22 for "strength" read length Signed and sealed this25th day of April 1961'.

( 3 EA L) Attest:

ERNEST W. SWIDER Atteeting Oflicer DAVID L, 'LADD I Commiesioner ofPatents

